Solute transport processes in the bentonite buffer of a deep geological repository for used nuclear fuel with thermal-hydraulic-mechanical coupling

Solute transport processes in the bentonite buffer of a deep geological repository for used nuclear fuel with thermal-hydraulic-mechanical coupling | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Research Article Solute transport processes in the bentonite buffer of a deep geological repository for used nuclear fuel with thermal-hydraulic-mechanical coupling Uy Dinh Vo, Mamadou Fall, Julio A. I. Seadano, Maiwenn Humbezi-Desfeux, and 3 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-9344613/v1 This work is licensed under a CC BY 4.0 License Status: Under Revision Version 1 posted 9 You are reading this latest preprint version Abstract This paper investigates solute transport processes in the bentonite buffer of a Deep Geological Repository (DGR) for used nuclear fuel, using the Canadian concept as an example. The design relies on a multi-barrier system, where the used fuel container (UFC) ensures containment, and the surrounding bentonite buffer seals gaps between the container and host rock. The buffer serves two key functions: (i) protecting the UFC against processes that may compromise containment, and (ii) retarding radionuclide migration in the event of UFC breach. Solute transport in the buffer is strongly influenced by coupled thermal-hydraulic-mechanical (THM) processes. A fully coupled THM-transport model was developed to evaluate two scenarios: (1) reactive transport of bisulfide \(\:\left({HS}^{-}\right)\) from the host rock to the UFC and its implications for long-term corrosion; and (2) radionuclide migration toward the host rock following a hypothetical breach. The model builds on previous verification and validation and is further validated here against laboratory-scale bisulfide transport experiments and a large-scale thermal diffusion experiment at the Tournemire Underground Research Laboratory (France). Model–data agreement demonstrates that adsorption and \(\:FeS\) precipitation significantly retard bisulfide migration, delaying detectable flux to the UFC by ~ 5×10⁵ years and limiting copper corrosion to ~ 0.05 mm over 1 Myr. Temperature-dependent diffusion is the dominant transport mechanism, while the Soret effect is negligible at repository scale. In the breach scenario, the buffer effectively delays and attenuates moderately/strongly sorbing radionuclides (e.g., 135 Cs, 237 Np). Overall performance is most sensitive to bentonite diffusivity and sorption capacity, highlighting key parameters for design and safety assessment. Full Text Additional Declarations No competing interests reported. Cite Share Download PDF Status: Under Revision Version 1 posted Editorial decision: Revision requested 27 Apr, 2026 Reviews received at journal 27 Apr, 2026 Reviews received at journal 16 Apr, 2026 Reviewers agreed at journal 13 Apr, 2026 Reviewers agreed at journal 11 Apr, 2026 Reviewers invited by journal 08 Apr, 2026 Editor assigned by journal 08 Apr, 2026 Submission checks completed at journal 08 Apr, 2026 First submitted to journal 07 Apr, 2026 You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. As a division of Research Square Company, we’re committed to making research communication faster, fairer, and more useful. We do this by developing innovative software and high quality services for the global research community. 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Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-9344613","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":622256518,"identity":"0a2784f8-3f23-4d37-ba85-a096a7eeba2e","order_by":0,"name":"Uy Dinh Vo","email":"","orcid":"","institution":"University of Ottawa","correspondingAuthor":false,"prefix":"","firstName":"Uy","middleName":"Dinh","lastName":"Vo","suffix":""},{"id":622256521,"identity":"92aa1aef-9468-4386-bd90-56cf0ed544bc","order_by":1,"name":"Mamadou Fall","email":"","orcid":"","institution":"University of Ottawa","correspondingAuthor":false,"prefix":"","firstName":"Mamadou","middleName":"","lastName":"Fall","suffix":""},{"id":622256523,"identity":"18852b94-6b65-4dd5-8624-e2b0aac6ed4b","order_by":2,"name":"Julio A. 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The design relies on a multi-barrier system, where the used fuel container (UFC) ensures containment, and the surrounding bentonite buffer seals gaps between the container and host rock. The buffer serves two key functions: (i) protecting the UFC against processes that may compromise containment, and (ii) retarding radionuclide migration in the event of UFC breach. Solute transport in the buffer is strongly influenced by coupled thermal-hydraulic-mechanical (THM) processes. A fully coupled THM-transport model was developed to evaluate two scenarios: (1) reactive transport of bisulfide \u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\(\\:\\left({HS}^{-}\\right)\\)\u003c/span\u003e\u003c/span\u003e from the host rock to the UFC and its implications for long-term corrosion; and (2) radionuclide migration toward the host rock following a hypothetical breach. The model builds on previous verification and validation and is further validated here against laboratory-scale bisulfide transport experiments and a large-scale thermal diffusion experiment at the Tournemire Underground Research Laboratory (France). Model\u0026ndash;data agreement demonstrates that adsorption and \u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\(\\:FeS\\)\u003c/span\u003e\u003c/span\u003e precipitation significantly retard bisulfide migration, delaying detectable flux to the UFC by ~\u0026thinsp;5\u0026times;10⁵ years and limiting copper corrosion to ~\u0026thinsp;0.05 mm over 1 Myr. Temperature-dependent diffusion is the dominant transport mechanism, while the Soret effect is negligible at repository scale. In the breach scenario, the buffer effectively delays and attenuates moderately/strongly sorbing radionuclides (e.g., \u003csup\u003e135\u003c/sup\u003eCs, \u003csup\u003e237\u003c/sup\u003eNp). Overall performance is most sensitive to bentonite diffusivity and sorption capacity, highlighting key parameters for design and safety assessment.\u003c/p\u003e","manuscriptTitle":"Solute transport processes in the bentonite buffer of a deep geological repository for used nuclear fuel with thermal-hydraulic-mechanical coupling","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2026-04-16 07:51:40","doi":"10.21203/rs.3.rs-9344613/v1","editorialEvents":[{"type":"communityComments","content":0},{"type":"decision","content":"Revision requested","date":"2026-04-27T21:30:01+00:00","index":"","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2026-04-27T05:27:50+00:00","index":"hide","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2026-04-16T09:09:28+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"14564130349106652225787226946781963355","date":"2026-04-13T04:54:48+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"298616622650437355131549089172805922585","date":"2026-04-11T04:16:16+00:00","index":"hide","fulltext":""},{"type":"reviewersInvited","content":"","date":"2026-04-09T03:22:13+00:00","index":"","fulltext":""},{"type":"editorAssigned","content":"","date":"2026-04-09T03:20:44+00:00","index":"","fulltext":""},{"type":"checksComplete","content":"","date":"2026-04-08T08:56:54+00:00","index":"","fulltext":""},{"type":"submitted","content":"Geotechnical and Geological Engineering","date":"2026-04-07T11:40:01+00:00","index":"","fulltext":""}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"geotechnical-and-geological-engineering","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"gege","sideBox":"Learn more about [Geotechnical and Geological Engineering](https://www.springer.com/journal/10706)","snPcode":"10706","submissionUrl":"https://submission.nature.com/new-submission/10706/3","title":"Geotechnical and Geological Engineering","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"em","reportingPortfolio":"Springer Hybrid","inReviewEnabled":true,"inReviewRevisionsEnabled":false}}],"origin":"","ownerIdentity":"2b86838b-39d9-4022-b20b-5f301f7a0758","owner":[],"postedDate":"April 16th, 2026","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"in-revision","subjectAreas":[],"tags":[],"updatedAt":"2026-04-27T21:39:04+00:00","versionOfRecord":[],"versionCreatedAt":"2026-04-16 07:51:40","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-9344613","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-9344613","identity":"rs-9344613","version":["v1"]},"buildId":"XKTyCvWXoU3ODBz1xrDgd","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}